Nicola Sturgeon has promised that a yes vote in next year's Scottish independence referendum could mean an earlier retirement date, as she deflected repeated attacks on its affordability.

The deputy first minister said an independent government would be likely to block plans by the British government to raise the state retirement age to 67 from 2026, suggesting too that a Scottish pension would be more secure and valuable.

Sturgeon, seeking to reassure pensioners that their incomes were secure, said: "We need to take these decisions based on Scottish circumstances. And that's the benefit of independence, we get to have Scottish solutions to particular Scottish issues rather than have solutions imposed on us."

Those pledges, published in a new Scottish government report, came under sustained attack on a series of fronts from its opponents and the British government after Sturgeon acknowledged she was unable to say how much those promises would cost.

The Department for Work and Pensions says failing to raise the pension age to 67 would cost Scotland £6bn by 2030.

The Scottish Tory party said the report failed to use recent official Scottish figures on the country's more rapidly ageing population, relying on older data, which meant a greater burden for a smaller number of working people in future.

The UK government said there were numerous "glaring gaps" in the report, with difficult questions "glossed over in the rush to make a 'guarantee' that pensions will still be paid on time".

The Scottish government's paper stopped short of promising that the retirement age would definitely be frozen but said "the rapid move to 67 is a concern". It would set up a new commission to investigate the affordability of a freeze at 66, the scope for reforms and new rules to encourage greater and mandatory saving towards pensions.

After arguing that Scotland was wealthier than the UK as a whole, Sturgeon told BBC Radio Scotland her government could only cost these policies once that commission had reported back. "We wouldn't take decisions that were unaffordable," she said.

Until then, Scotland would largely copy the UK's state pensions system, but with additional income guarantees which would have little immediate impact on affordability, and would negotiate to keep a pan-Britain regulatory system for occupational pensions.

It made clear, however, it favoured a freeze at 66 because Scottish men on average die 2.5 years earlier than the UK average, and women 1.8 years earlier. Sturgeon insisted that Scotland was wealthy enough to afford a more generous state system, designed to the country's specific needs. In the only costed pledge in the pensions paper, she said a future Scottish government under Scottish National party control would keep the "triple lock" which ensures pensions rise in step with living costs after the 2016 Scottish election.

In the first year of that government, Scotland's state pensions and pensions credit bill would be £8.2bn, compared wtih £7.3bn in 2011-12. The UK government's "triple lock" policy lasts until the 2015 general election.

Her government's critics pointed to stark warnings about the affordability of pensions after independence in a leaked Scottish cabinet memo written last year by John Swinney, the Scottish finance secretary.

Swinney admitted in that confidential memo that the "ageing profile of our population" and Scotland's reliance on volatile oil revenues could mean serious cost pressures on an independent state's spending.

His government was accused by Labour of a further retreat after the Scottish government admitted it would need EU agreement to amend strict rules on cross-border pensions which could otherwise lead to multibillion-pound costs for many of the pan-UK pension funds.

Earlier this year, Alex Salmond, the first minister, denied Scotland would need any help with EU pensions rules after experts warned that the numerous pan-UK pension funds would need to find tens of billions to make sure they were fully funded after independence.

Gregg McClymont, Labour's shadow pensions minister, said: "Alex Salmond promised us that private pensions were not at risk due to EU cross-border regulations and that Scotland would not need to seek a special deal from the EU. Today he has broken that promise.

"We have waited for months and now they finally admit that Scotland would need to ask 28 other EU countries for a special deal that they themselves would not have. It just isn't a credible plan."

But, after changing tack on that point, the Scottish government was given a boost by the ICAS after the institute supported its calls for both governments to start talks immediately on how to solve that problem.